As is known in the art, infrared photon detectors (also referred to as a photo-detector) based on narrow bandgap semiconductors are susceptible to performance degradation due to noise thermally generated by charge carriers masking signal carriers generated by incident photon radiation. This noise is typically characterized by high dark current densities in photovoltaic and photoconductive infrared detectors and can lead to decreased sensitivity of the device. To mitigate thermal noise effects, photo-detectors are typically cooled to cryogenic temperatures using large and expensive systems. Such cooling systems limit the ability of the detector package to meet size, weight, power, and cost constraints of certain applications.
The relationship between detector volume and dark current density is well known and device designs and material parameters that determine detector volume are traditionally optimized to achieve desired performance requirements. More particularly, infrared photo-detectors based on narrow bandgap semiconductors are susceptible to thermally generated noise, resulting in signal-to-noise ratio reduction. Reducing photo-detector volume results in lower dark current density (thermal noise) in narrow bandgap semiconductors due to fewer available charge carriers. However, reducing the photo-detector volume also results in low photon absorption due to reduction in absorptive material.
Device architectures designed to reduce material volume for thermal noise reduction use classical designs and techniques such as non-equilibrium detector architectures for alloys, superlattice and barrier structures, and absorber layer thinning. However, these architectures used singularly compromise photon absorption due to the reduction in detector material.